Whole cell amperometric biosensor based on Aspergillus niger for determination of glucose with enhanced upper linearity limit

Whole cells of Aspergillus niger strain CCM 8004 containing glucose oxidase (E.C. 1.1.3.4.) were used for the preparation of a glucose biosensor. The microorganism was entrapped in a dialysis membrane attached to the Clark oxygen electrode. The upper linearity limit of the sensor was improved by the presence of hydrogen peroxide. At a concentration of H2O2 equal to 8 mmol l−1 the upper linearity limit increased by 10 times without marked influence on the sensitivity of the sensor. Influences of pH and temperature on the sensor response were tested. The selectivity of the biosensor on various saccharides was evaluated and it was found that only maltose gives a response from tested saccharides. As to the operational and storage stability, a continuously used sensor lost 25% of its initial sensitivity after 20 days, the storage stability was at least two months. Because of good selectivity, the sensor has been used for the determination of glucose in whey (after hydrolysis of lactose) during fermentation of Xanthomonas campestris. A good correlation between data determined by the enzymatic kit as well as by liquid chromatography with the whole cell amperometric biosensor was obtained.